Fix about_symbols koan

* :symbol is syntax for symbol

[#54145643]
Fix about_symbols koan

* symbols can be compared

[#54145643]
Fix about_symbols koan

* identical symbols are a single internal object
  and have the same object_id

[#54145643]
Fix about_symbols koan

* method names become symbols

[#54145643]
Fix about_symbols koan

* Constants do NOT become symbols

[#54145643]
Fix about_symbols koan

* symbols can be made from strings w/ .to_sym

[#54145643]
Fix about_symbols koan

* strings with space can become symbols

* "test symbol".to_sym == :"test symbol"

[#54145643]
Fix about_symbols koan

* #{} interpolation can be used in symbols

[#54145643]
Fix about_symbols koan

* calling .to_s on symbols drops the ':', when
  interpolated into strings

[#54145643]
Fix about_symbols koan

* :symbols are not strings, and not equivalent

* i.e. :ruby is not the same s "ruby", even if 
  it can be #{} in a string.

[#54145643]
Fix about_symbols koan

* symbols do not respond to string methods

* symbols are immutable

[#54145643]
Fix about_symbols koan

* symbols cannot be concatenated

* will raise NoMethodError

[#54145643]
Fix about_symbols koan

* Symbols can be dynamically created out of
  strings, e.g. ("cats" + "dogs").to_sym

[#54145643]
Merge pull request #8 from bayendor/54145643_about_symbols_master

Fix about_symbols koan

[Delivers #54145643]